Air conditioning system



Oct. 29, 1935. K. P BRACE ET AL AIR CONDITIONING SYSTEM Filed April 29,1933 INVENTOR- iElIPEK I? EARL arm 1.. Fave, 3nd. By fin fio d'lm. 1 vATTORNEYS- Patented a. 29,1935

UNITED STATES AIR CONDITIONING SYSTEM Kemper P. Brace, New York, N. Y.,and Norman -L. Rowe, 3d, Jersey City, N. J., assignors to AirConditioning Systems Inc., New York, N. Y., a corporation of New YorkApplication April 29, 1933, Serial No. 668,510

14 Claims.

This invention relates to air conditioning systems, and moreparticularly to air conditioning systems wherein the tempering andhumidifying of the air is accomplished without the use of mechanical,refrigeration.

In its preferred embodiment the present invention comprises an airconditioning system wherein a primary air stream is precooled by passingit over coils containing circulating cold water, where it may also bedehumidified to some extent, and is then mixed with return air from theenclosure wherein desired conditions of temperature and humidity are tobe maintained, and the mixed air stream is passed to a dehydratingchamber. In this chamber, the air is brought into intimate contact witha dehydrating solution to dehumidify the air. From the dehydratingchamber the dehumidified air is passed over a recooling coil and thenceinto the enclosure.

One of the main objects of the present invention is to effectdehumidiflcation of the air without substantially changingitstemperature. This is accomplished by the isothermal dehumidificationproduced in the dehydrating chamber. By passing the solution used in thedehydrating chamber through a solution cooler, the heat of condensationof the moisture from the air, and the heat of dilution of the solution,may be removed from the solution so that a substantially constanttemperature is maintained in the dehydrating chamber.

In connection with the use of a dehydrating solution, it is anotherobject of the present invention to provide means for maintaining thissolution at a substantially constant concentration by passing the dilutesolution through a boiler wherein the absorbed moisture is liberatedfrom the solution and the concentrated solution is then returned,through a heat interchanger and the solution cooler, to the dehydratingchamber.

Another object of the present invention resides in the cooling of thefresh air stream and the mixed air stream without the use of mechanicalrefrigeration by passing the air streams over heat exch ge means havingcold water circulating therethrough, the circulation of the water beingcontrolled in accordance with the temperature desired within theenclosure. 7

The system as a whole is provided with various controls, which efiectoperation of the cooling and the dehumidifying means in accordance withthe temperature and humidity conditions which it is desired to maintainwithin the enclosure.

- Another object of the present invention is the provision of an airconditioning system of simple and compact arrangement, and of decidedlyeconomical construction, since the refrigerating load ordinarilyrequired in such a system is eliminated, and also, the heatingmeans forreheating the air after dehumidification by lowering the temperaturethereof, as has been the practice heretofore, is eliminated by the useof the isothermal dehumidifying means.

Other objects and advantages of the present invention will appear morefully from the following detailed description, which, taken inconnectionwith the accompanying drawing will disclose to those skilled in the arta preferred embodiment of our invention.

The drawing discloses a substantially diagram- 15 matic representationof the air conditioning system of the present invention.

Referring now in detail to the operation of the invention, in thedrawing we have provided the enclosure or space I in which it is desiredto maintain predetermined conditions of temperature and humidity. Thisenclosure is provided with the outlet 2, which communicates with aconduit containing fresh air admitted at the inlet opening 3 thereof.

The fresh primary air stream entering the inlet 3 passes over theprecooling coil 8, which may comprise an extended surface cooling coilof finned construction, through which cold water is adapted to becirculated. The air leaving the coil 4 passes through the conduit 5 andis mixed with the return air from the conduit 2, the mixture passingthrough the conduit 6 to the dehydrating chamber 1.

This dehydrating chamber 1 may comprise any desired gas and liquidcontact apparatus, in which the mixed air stream comes into contact witha concentrated solution of a dehydrating medium, such as calciumchloride, lithium chloride, or other hygroscopic salt solutions,preferably moving in counter-current relation to the flow of air. Forexample, the apparatus may comprise a series of spaced rotating discsadapted to present films of the solution to the passing air stream,cloth sheets or other means providing for temperature is not greatlychanged. the' dehumldification being substantially isothermal.

The dehydrated air leaving the dehydrating chamber I passes through theduct 8 to a second cooling coil 9, preferably termed a recooling coil",which is similar in construction to the coil 4, and which is adapted tocool the mixture of dehydrated air sufliciently to produce the propertemperature within the conditioned space or enclosure I. From therecooling coil 9, the cooled conditioned air passes through the duct IIIto the fan I I, by which it is forced through the inlet duct I2 into theenclosure I. Suitable manual orautomatically controlled dampers may beprovided adjacent the outlet conduit 2, the fresh air inlet conduit 3,and the connection of the conduit 2 and the conduit 5, for providingpredetermined proportions of fresh and return air.

The water used in the precooling coil 4 and the recooling coil 9 issupplied through a water supply main I3, which may be connected to anydesired source of cold water, and which is provided preferably with thebranch supply lines I4, I5 and I6, which respectively supply therecooling coil 9, a solution cooler 20, and the precooling coil 4.

In order to provide circulation through the dehydrating chamber I, apump II, which may be any desired type of pump, operated either bymechanical or electrical means, is connected between the suction oroutlet pipe I8 of the dehydrating chamber and the discharge pipe I9 ofthe pump, which pipe I9 extends through the solution cooler 20 andconducts the pumped solution to the dehydrating chamber I. The solutioncooler 20 is supplied with cold water through the supply pipes I5 and2|. of condensation of moisture from the air, and the heat of dilutionof the dehydrating solution which is contained in the solution, by heattransfer between the water and the solution, and is preferably acounter-current extended surface cooler of any well known type.

The absorbing or dehydrating solution used in the chamber 1 isconstantly being diluted by the absorption of moisture from the airstream, and consequently, some means must be provided for removing theabsorbed moisture. This is accomplished by conducting a portion of thesolution from the discharge side of the pump I! through the conduit 22to a boiler 24, the pipe 22 extending through a heat interchanger 23, tobe hereinafter described in'more detail. In the boiler 24, the moistureis continually removed from the solution by evaporation, and thesolution is thus concentrated. Theconcentrated solution is returnedthrough the pipe 25, heat interchanger 23,

conduit 28 and a pump 21 to a conduit 28 leading back into the mainsupply line I9 of the dehydrating chamber I. In this manner, a constantconcentrating of the solution is efiected, and the concentrated solutionis returned into the dilute solution being discharged from the pump II.The heat interchanger 23 serves to impart a' portion of the heat of theconcentrated solution leaving the boiler 24 to the incoming solutionentering through the pipe 22. .By this interchanging of the heatfrom theconcentrated solution to the incoming dilute solution, a considerablesaving of heat energy is eifected.

In order to effect automatic control of the temperature conditionsdesired within the enclosure I, we preferably provide a thermostat 29,responsive either to dry bulb or wet bulb temperatures,

.which may be located in either the enclosure ,I,

or-adjacent the outlet therefrom into the conduit This cooler serves toremove the heat 2, and which is connected through the tube 30 or thelike, which may be a suitable compressed air pipe or other actuatingmeans, to the diaphragmof a three-way valve 3| which controls the (lelivery of cold water from the branch supply line 5 I4 to the-recoolingcoil 9. The valve 3| is of any desired type, and is operated by thethermostat 29 in such manner that when the temperature within theenclosure I rises above theidesired temperature conditions, the'valveadmits more 10 cold water from the branch supply line |'-'4 through theconduit 32 to the coil 9. However, when the temperature within theenclosure I drops below-- the predetermined desired condition, the valveis operated to pass the cooling water from the branch 15 supply line I4through the conduit 33 to the outlet side of the cooling coil 9, andthence to a suitable drain. If desired, the thermostat29 may be of suchcharacter as to energize electrically operated means for controlling thevalve 3|.::

The humidity desired within the enclosure is controlled, preferably, bya humidostat or wet bulb thermostat 34, disposed in the conduit 2, oradjacent the enclosure I, and which is connected, through the pressureline 35 to a valvef36 of the 25 same construction as the valve 3|. Thevalve 36 is adapted to control the flow of water to the solution cooler.Thus, if an increase in the absolute humidity is necessary to providethe proper humidity within the enclosure I, the valve 36 30 throttlesthe flow of cooling water through the pipe-2|, and causes the water fromthe branch supply main I5 to pass through the pipe 31 to the outlet sideof the solution cooler 20. In this manner, the temperature and vaporpressure of the 35 dehydrating solution is increased, resulting in lessdehumidification being efiected within the dehydrating chamber I. When adecrease in the absolute humidity is desired, in order to maintain theproper humidity conditions within the enclosure 40 I, the valve 36 isactuated by the humidostat 34 to allow more cooling fluid to flowthrough the pipe 2| to the solution cooler 20, and thus produce alowering of the temperature of the dehydrating solution, which resultsin a greater dehumidiflca- 5 tion being effected within the dehydratingchamber I. In this manner, the control of the temperature of thedehydrating solution results in automatic control of thedehumldification effected, and thus results in control of the humiditywith- 60 in the enclosure I.

The cooling coils 4 and 9, and the solution cooler 28 preferably havetheir discharge openings connected by suitable means to acommon drain44, and the warmed water is thus carried away to waste, or for use inother situations.

A supplemental control for the humidity within the enclosure may beprovided by disposing a dewpoint thermostat 42 in the path of thedehydrated air stream, preferably in conduit 8, as shown. The thermostat42 is connected, through line 43 to a suitable valve 38, correspondingto the valves 3| and 36. The valve 38 is adapted to control the flow ofdehydrating solution to the chamber I, and bypasses a portion of thesolution when it is desired to effect less dehumldification within thedehydrating chamber I.

It is thus apparent that regulation of the amount of dehumldificationtaking place within the chamber I is controlled, either by thehumidostat 34, or by the dewpoint thermostat 42. It is apparent tliatthecontrol 34 may be used for throttling the flow of the solution, and thecontrol 42 for determining the temperature of the solution, if desired.

To' eflect control of the concentration of the" solution produced withinthe boiler 24, a thermwtat 89 is placedin direct contact with thesolution in the boiler, and is set for a tempera.- ture corresponding tothe boiling point of the solution at the desired concentration. Thethermostat 39 is connected through suitable means 40 to the fuel supplyvalve 4| which admits fuel to the burner of the boiler. It is apparent,that, by the provision of the thermostaticcontrol of the boiling pointof the solution within the boiler 24, the desired concentration of' thesolution can be produced.

In connection with the controls 29, 34, 82 and 39, it is to beunderstood that any suitable type of control may be used, which mayactuate either electrical, mechanical or pressure means for effectingcontrol of the valves 3|, 36, 38 and M, respectively.

In the operation of the control shown for the boiler 24, a certainquantity of water is at all times being absorbed by the solution in thechamber I. At the same time, a substantially equal quantity of theabsorbed moisture is being evaporated in the boiler 24 at a temperaturecorresponding to the concentration desired. The pumps I! and 21 arecirculating substantially constant quantities of the solution. Now, ifdue to a change in the condition of the air passing through the duct 6to the dehydrating chamber 1, the amount of moisture absorbed in thechamber 1 becomes less, the concentration of the solution in the boiler24 will tend to increase. However, this will in effect, tend to raisethe boiling point of the solution. The thermostat 39, in such instances,will throttle the valve 4| and reduce the amount of fuel supplied to theboiler,

thus decreasing the amount of water removedfrom the solution, andthusmaintaining the concentration constant.

It is therefore apparent that we have provided an air conditioningsystem wherein the air is dehumidified without substantially chang ingits temperature, thus eliminating the use of mechanical refrigeratingmeans for lowering the temperature of the air stream to a pointsuflicient to produce the desired dehumidification. This effects aconsiderable saving by the elimination of the refrigerating load imposedupon such a system. Further, we have provided a system wherein thecooling of the air is accomplished by circulation of cold water throughsuitable cooling coils in direct heat exchange contact with the airstream. This eliminates the use of artificial refrigerating means. Thecontrols for maintaining the desired conditions of temperature andhumidity within the enclosure are automatic in operation, and need noattention other than initially setting them to the desired point.

While we have shown and described a preferred embodiment of ourinvention, we do not intend to be limited to the exact detailsdisclosed, but only in so far as defined by the spirit and scope of theappended claims.

We claim:

1. The method of conditioning air for an enclosure which comprisesprecooling a stream of fresh air, mixing said precooled fresh air withreturn air from said enclosure, isothermally dehydrating said mixturewith a dehydrating solution, controlling the temperature of saidsolution in accordance with the humidity of said return air, recoolingsaid dehydrated air, and delivering said air to the enclosure.

2. The method of conditioning air for an enclosure which comprisesprecooling a. stream of fresh air, mixing said precooled fresh air withreturn air from said enclosure, isothermally dehydrating said mixture byintimate contact with a dehydrating solution, controlling the quantity 6of said solution contacted in accordance with the humidity of thedehydrated air, recooling said dehydrated ainand delivering said air tothe enclosure.

3. The method of conditioning air for an en- 10 3 closure whichcomprises precooling a stream of fresh air, mixing said precooled freshair with return air from said enclosure, isothermally dehydrating saidmixture by intimate contact with Y a dehydrating solution, controllingthe quantity of said solution contacted in accordance with the humidityof the dehydrated air, recooling said dehydrated air, controlling therecooling of said dehydrated air in accordance with the dry bulbtemperature of the air in said enclosure, and delivering said dehydratedair to the enclosure.

4. The method of conditioning air for an enclosure which comprisesprecooling a stream of fresh air, passing said air into intimate contactwith a dehydrating solution controlling the temperature of said solutionin accordance with the wet bulb temperature of the air in saidenclosure, subsequently cooling said dehydrated air in accordance withthe temperature in said enclosure, and delivering said air to theenclosure.

5. The method of conditioning air for an enclosure which comprisesprecooling a stream of return air by admixture with cooled fresh air,passing said air into intimate contact with a dehydrating solution,controlling the quantity and temperature of said solution passed intocontact with said air, subsequently recooling said dehydrated air inaccordance with the temperature in said enclosure, and delivering saidair to the enclosure.

6. The method of conditioning air for an enclosure which comprisesprecooling a stream of fresh air, mixing said air with return air,passing the mixture into intimate contact with a dehydrating solution,controlling the circulation of said dehydrating solution in accordancewith the relative humidity of the air in said enclosure, and recoolingsaid dehydrated air.

7. The method of conditioning air for an enclosure which comprisesprecooling a stream of fresh air, mixing said air with return air,passing the mixture into intimate contact with a dehydrating solution,controlling the circulation of said dehydrating solution in accordancewith the relative humidity of the air in said enclosure, recooling saiddehydrated air, and controlling the recooling of said air in accordancewith the dry bulb temperature of said return air.

8. The method of conditioning air for an enclosure which comprisesprecooling a stream of fresh air, mixing said air with return air,passing the mixture into intimate contact with a dehydrating solution,controlling the temperature of said dehydrating solution in accordancewith the relative humidity of the air in said enclosure, recooling saiddehydrated air, and controlling the recooling of said air in accordancewith the dry bulb temperature of said return air.

9. The method of conditioning air for an enclosure which comprisesprecooling a stream of fresh air, mixing said air with return air,passing the mixture into intimate contact with a dehydrating solution,controlling the circulation of said dehydrating solution in accordancewith the relative humidity of the air in said enclosure, re-

cooling said dehydrated air, and controlling the recocling of said airin accordance with the wet bulb temperature of said return air.

10. The method of conditioning air for an en-- closure which comprisesprecooling a stream of fresh air, mixing said air with return air,passing the mixture into intimate contact with a dehydrating solution toabsorb moisture therefrom, controlling the temperature of saiddehydrating solution in accordance with the wet bulb temperature of theair in said enclosure, and subsequently recooling the dehydrated air.

11, The method of conditioning air for an enclosure which comprisesprecooling a stream of fresh air, mixing said air with return air,passing the mixture into intimate contact with a dehydrating solution toabsorb moisture therefrom, controlling the circulation of saiddehydrating solution in accordance with the humidity conditions desiredwithin said enclosure, and subsequently recooling the dehydrated air.

12. The method of conditioning air for an enclosure which comprisesprecooling a stream of fresh air, mixing said air with return air,passing the mixture into intimate contact with a dehydrating solution toabsorb moisture therefrom, controlling the circulation of saiddehydrating solution in accordance with the dewpoint temperature of thedehydrated air, and subsequently recooling said air.

13. The method of conditioning air for an enclosure which comprisesprecooling a stream of fresh air, passing said air mto intimate contactwith a dehydrating solution, circulating the solution throughevaporating means to remove absorbed moisture therefrom, maintaining theconcentration of said solution constant by controlling the temperatureof said evaporating means, cooling said concentrated solution,controlling the quantity of said solution which passes into 10 contactwith the air stream inaccordance with the dewpoint of the dehydratedair, and recooling said dehydrated air;

14. The method of conditioning air for an enclosure which comprisesmixing fresh air with 15 return air from said enclosure, intimatelycon-Z tacting said air with a dehydrating solution, maintaining saidsolution at a constant concentration, controlling the temperature ofsaid solution in accordance with the humidity of said re- .0

turn air, recooling said dehydrated air, controlling the circulation ofsaid solution in accordance with the dewpoint of the dehydrated airprior to the recooling thereof, and delivering said cooled dehydratedair to said enclosure. .5

KEMPER P. BRACE. NORMAN L. ROWE, 3RD.

